Box spring assemblies may be as simple as a fabric covering over a simple wooden framework. More typically, a box spring assembly has a lower wooden framework to which is attached a plurality of spring elements. These spring elements are selectively attached to one another to form a unified structure. Padding, usually quilted to a decorative fabric, covers the top surface of the spring elements to form a top cover. An additional side fabric portion is sewn to this top cover to extend about the sides of the box spring assembly. This side fabric portion is typically attached to the wooden framework on the bottom of the box spring assembly. This side fabric portion is attached to the wooden framework by staples, nails, tacks or adhesive. The attachment operation is usually performed manually by inverting the box spring, pulling the fabric covering tight and stapling the fabric to the wooden framework. This manual operation is expensive because it is labor intensive and the quality of the attachment is dependent upon the operator.
Several devices have been developed to attach flexible coverings, such as fabric, to semi-rigid or rigid members, such as the framework of box springs. One of the problems with an automated assembly machine is the variety of sizes of box springs which need to be accommodated. Box springs are manufactured in at least four standard sizes with a host of non-standard sizes. Typical standard sizes are: single or twin, which is thirty eight (38) inches by seventy four (74) inches; full or double, which is fifty three (53) inches by seventy four (74) inches; queen, which is sixty (60) inches by eighty (80) inches; and king, which uses two box springs measuring thirty eight (38) inches by eighty (80) inches each. The thickness of the box springs is not as standardized as the length and width. The thickness of the box spring is dependent upon the type of support elements and the type and thickness of the top cover.
An apparatus to attach a flexible cover to a semi-rigid member is disclosed in Wortsmith, U.S. Pat. No. 3,527,397. The '397 patent discloses a machine used to staple a covering to a kneeling bench. A fixed height table supports a fixture holding the elements to be assembled. A series of drive wheels are located on the table with a series of non-driven rollers positioned parallel to the drive wheels to complete the table top. A series of pressure wheels are located above the table to compress the article to be assembled. Rotating brushes turn the flexible covering down upon the frame, whereupon a pair of staple guns oscillate up and down to force a staple through the covering fabric into the frame each time the staple guns strike the article. Adjustment of the machine for different size articles, although possible, is time consuming because each element of the machine must be adjusted separately.